JPWO2014092067A1 - Polyglycolic acid solidified extruded product and method for producing the same - Google Patents

Abstract

It is formed from a resin material containing polyglycolic acid (PGA) having a weight average molecular weight of 100,000 to 300,000, melt viscosity (temperature 270 ° C, shear rate 120sec-1) 100 to 2,000Pa · s, and has a tensile strength of 20 at 150 ° C. A PGA solidified extrusion of ~ 200 MPa; an oil drilling downhole tool or member thereof formed by machining the solidified extrusion; a sealing plug comprising the member; a core plug of the sealing plug; and The resin material is supplied to an extruder (preferably from a quantitative feeder), and after solidification extrusion molding, the solidified extrudate is pressurized and taken up while applying back pressure in the forming die direction to suppress expansion of the solidified extrudate. A method for producing a PGA-solidified extruded product including a process, and a method for producing a downhole tool or a member thereof.

Description

  The present invention relates to a polyglycolic acid-solidified extruded product and a method for producing the same, and more specifically, a wall thickness or a large diameter that can be formed into a secondary molded product having a desired shape by machining such as cutting, drilling, and cutting. The present invention relates to a polyglycolic acid solidified extruded product and a method for producing the same.

  A resin molded product having a three-dimensional shape or a complicated shape is generally molded by injection molding. According to injection molding, a molded product having a desired shape can be mass-produced. However, in order to produce a molded product requiring high dimensional accuracy by injection molding, an expensive mold having high dimensional accuracy is required. Moreover, since the injection-molded product is easily deformed due to shrinkage and residual stress after injection molding, it is necessary to precisely adjust the mold shape according to the shape of the molded product and the characteristics of the resin material. In injection molding, since the defect rate is high, the product is often expensive. Further, in injection molding, it is difficult to mold a molded product having a large thickness because of shrinkage and residual stress.

  In order to obtain a molded product with a three-dimensional shape or a complicated shape, a resin material is extruded and processed into various shapes such as flat plates, round bars, pipes, odd-shaped products (“cutting materials” and There is known a method of forming a secondary molded product having a desired shape by manufacturing a machining material such as cutting, drilling, and cutting. The machining method for machining materials does not require expensive molds, so that it is possible to manufacture molded products with a small production volume at a relatively low cost, to respond to frequent changes in the specifications of the molded products, and to improve dimensional accuracy. Advantages include that a high molding can be obtained and that a molding having a complicated shape and a large thickness that are not suitable for injection molding can be produced.

  However, any resin material or extruded product is not suitable for machining materials. For machining materials, for example, thickness is excellent in machining suitability, residual stress is small, excessive heat is not generated due to frictional heat generated during machining, deformation and discoloration, and machining with high accuracy It is required to satisfy a high degree of required characteristics such as being able to

  For machining of polymer materials, most of the processing methods used for metal materials are generally used as they are. Even if it is an extrusion molded product, a thin and highly flexible material such as a normal film, sheet, or tube is not suitable for machining such as cutting. Even if the extruded product has a shape such as a flat plate or round bar with a large thickness or diameter, the extruded product with excessive residual stress at the time of extrusion is easily deformed at the time of machining or after machining. It is difficult to obtain a high secondary molded product. Even extruded products with reduced residual stress are not suitable for machining materials if they are prone to cracking or cracking during machining such as cutting, drilling or cutting.

  In order to obtain a machining material having characteristics suitable for machining by extrusion molding, it is necessary to devise a selection of a resin material, an extrusion molding method, and the like. Therefore, conventionally, various proposals have been made on extrusion methods for producing extruded products suitable for machining materials using resin materials containing general-purpose resins and engineering plastics.

  For example, Japanese Patent Application Laid-Open No. 2005-226031 (Patent Document 1) discloses a resin composition containing engineering plastics such as polyether ether ketone, polyether imide, polyphenylene sulfide, polysulfone, polyether sulfone, and polycarbonate. Thus, a method of manufacturing a machining material having a thickness or diameter exceeding 3 mm is disclosed.

  On the other hand, biodegradable plastics are attracting attention as environmentally friendly polymer materials, and their applications are expanded to extrusions such as films and sheets, blow moldings such as bottles, and injection moldings. In recent years, there has been an increasing demand for application of biodegradable plastics to machining materials.

  Polyglycolic acid has superior crystallinity in terms of tensile strength, tensile elongation, bending strength, flexural modulus, hardness, flexibility, heat resistance, etc., compared to other biodegradable plastics such as polylactic acid It is a biodegradable plastic that has a gas barrier property comparable to or surpassing that of a general-purpose gas barrier resin. Polyglycolic acid can be formed into a film or sheet by extrusion. For example, Japanese Patent Laid-Open No. 10-60137 (Patent Document 2) discloses a method of forming polyglycolic acid into a sheet by extrusion molding. The sheet has a thickness of 0.01 to 5 mm, and it is disclosed that various sheet molded products are produced by utilizing characteristics such as toughness, heat resistance, and transparency.

Furthermore, Japanese Patent Application Laid-Open No. 2010-69718 (Patent Document 3) discloses a polyglycolic acid solidified extrudate having a thickness or diameter of 5 to 100 mm obtained by solidifying and extruding polyglycolic acid. Specifically, it is formed from a resin material containing polyglycolic acid having a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 10 to 1,500 Pa · s, particularly preferably 70 to 900 Pa · s, Polyglycolic acid solidified extrudates having a density of 1.575 to 1.625 g / cm ³ and a thickness or diameter of 5 mm to 100 mm are disclosed.

  By the way, due to the growing interest in resource constraints, carbonization from the formation including hydrocarbon resources (sometimes referred to simply as “oil” in the present invention) such as petroleum (shale oil, etc.) and gas (shale gas, etc.). The recovery of hydrogen resources has been further deepened, and downhole tools or members thereof used for the formation, repair, or promotion of resource recovery of downholes (underground excavations) provided for that purpose, namely, The physical properties required for downhole tool members are more severe. For example, a method of hydraulic fracturing (fracturing) is widely used in a horizontal well formed by being embedded substantially horizontally in a shale layer or the like exceeding 1,000 m underground. With downhole drilling, the ball sealer, which is a downhole tool member that keeps drilling (fracture) formed by hydraulic fracturing, and the downhole tool installed in the downhole to perform hydraulic fracturing Some plugs such as flack plugs, bridge plugs, packers, etc. are used to check the location near the tip of the downhole or the location where hydraulic crushing has been performed previously, and perform new or renewed hydraulic crushing, After the drilling (fracture) is formed, it can be recovered or destroyed and used to extend well drilling or subsequently hydraulically crush elsewhere. Therefore, a downhole tool such as a sealing plug and a downhole tool member provided therein have strength (for example, tensile strength) that can withstand hydraulic crushing and laying, and cost and ease of recovery or destruction are required.

  Seal plugs such as flap plugs, bridge plugs, packers, cement retainers, etc. are usually constructed by attaching rubber seal members around the core of the plug. Exhibits a sealing action when the rubber is deformed by the tension and / or compression of the core rod [US Patent Application Publication No. 2005/205266 (Patent Document 4)]. The size of the core rod of the plug is formed to an arbitrary predetermined outer diameter as long as the inner diameter of the down hole is maximized and a rubber sealing member can be attached to the periphery. is there. Further, the core rod of the plug is usually hollow to allow muddy water to pass, and the hollow diameter is often 10 to 50 mm, typically 19.1 mm (0.75 inch), 25.4 mm (1 inch). ) 31.8 mm (1.25 inches), for example, a pipe-like shape having a length of about 1,000 mm is used as the main part, and the core bar is tensioned and / or compressed at both ends. It is a shape provided with an enlarged diameter part so that a tool can be engaged. In the tension and / or compression of the plug core rod, about 2,000 to 5,000 kgf (about 19,600 to 49,000 N), often about 2,500 to 4,500 kgf (about 24,500 to 44, 100N) is applied to the core rod, and in particular, the above-mentioned expanded diameter portion (engagement portion with the jig) of the core rod has a stress concentration of 2 to 5 times. It is necessary to select a material that can withstand the strength.

  On the other hand, after the hydraulic crushing, a method of recovering the sealing member or destroying the core rod to form the opening is employed. Conventionally, a metal such as cast iron has been used as the core rod of the plug. Therefore, it is expensive to collect the plug, and it is difficult and expensive to break the metal core rod. . Therefore, an epoxy resin composite material or the like is also used as a plug core rod. However, a resin composite material such as an epoxy resin composite material is not sufficient in strength and requires a high cost for collecting the sealing material, and is the same as a resin or a reinforcing material (carbon fiber, Since metal fibers and the like are non-degradable, they have a problem that they cannot be treated or discarded. In particular, the ground temperature gradient (underground heating rate) in the basement (in the crust) is said to be about 3K / 100m, and in the recent downhole reaching 3,000m underground, it becomes a high temperature environment exceeding about 100 ° C. There is a demand for a sealing material having sufficient strength such as tensile strength under such a high temperature environment.

  The use of degradable plastics is expected because the downhole tool or its member can be collapsed by being left in the downhole without being collected on the ground after use. Specifically, there is a need for a degradable plastic that has sufficient strength in a high temperature environment exceeding 100 ° C. and that can be processed into a desired shape by machining, and a downhole tool or a member thereof formed therefrom. And a method for producing the same.

JP 2005-226031 A (corresponding to US Patent Application Publication No. 2008/038517) Japanese Patent Laid-Open No. 10-60137 JP 2010-69718 A US Patent Application Publication No. 2005/205266

  An object of the present invention is to form a secondary molded article having a desired shape by machining such as cutting, drilling, cutting, etc., particularly a downhole tool provided in a sealing plug or a member thereof. An object of the present invention is to provide a decomposable resin-solidified extruded product having sufficient strength in the environment and a method for producing the same.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have optimized the molecular weight of polyglycolic acid, the melt viscosity and the tensile strength at a specific temperature, and the solidification extrusion molding conditions, in particular, solidification. By pressing the extrudate and controlling expansion in the thickness direction or diametric direction of the solidified extrudate, it can be formed into a downhole tool such as a sealing plug or a member thereof that can be used in a high temperature environment. It was found that a degradable resin-solidified extrudate, specifically a polyglycolic acid-solidified extrudate, could be obtained, and the present invention was completed.

That is, according to the present invention, polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity of 100 to 2,000 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is obtained. There is provided a polyglycolic acid solidified extrudate formed from a resin material to be contained and having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa.

Moreover, according to this invention, the polyglycolic acid solidification extrusion molding of the following (1)-(4) is provided as an embodiment.
(1) The polyglycolic acid solidified extruded product having a round bar, hollow or flat plate shape.
(2) The polyglycolic acid-solidified extruded product, wherein the resin material is a polyglycolic acid composition containing 0.001 to 5% by mass of a colorant based on the total amount.
(3) The polyglycolic acid solidified extruded product, wherein the resin material is a polyglycolic acid composition containing 5 to 70% by mass of a filler based on the total amount.
(4) The polyglycolic acid solidified extruded product, which is a material for machining.

  Furthermore, according to the present invention, there is provided a downhole tool for oil drilling or a member thereof formed by machining the polyglycolic acid solidified extruded product, and further, the downhole tool member for oil drilling is provided. The above-described oil drilling downhole tool member, which is a sealing plug or a core rod of the sealing plug, is provided.

In addition, according to the present invention, the following steps 1 to 4;
a) A resin material containing polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 100 to 2,000 Pa · s, Step 1 of supplying to an extruder and melt-kneading at a cylinder temperature of 220 to 285 ° C. of the extruder;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the forming die direction, and at this time, expansion in the thickness direction or diameter direction of the solidified extrudate is suppressed by pressurization to obtain a polyglycolic acid solidified extrudate. Step 4;
A method for producing a polyglycolic acid-solidified extruded product having a tensile strength at a temperature of 150 ° C. containing 20 to 200 MPa is provided.

And according to this invention, the manufacturing method of the polyglycolic acid solidification extrusion molding of the following (i)-(vi) is provided as an embodiment.
(I) The said manufacturing method which supplies the resin material containing the said polyglycolic acid to an extruder in the said process 1 using a fixed quantity feeder.
(Ii) In step 3, using a forming die in which heating means is arranged in addition to cooling means, first, the molten extrudate in the flow path near the extrusion die outlet is heated to a temperature of 230 to 290 ° C. by the heating means. And then solidifying the molten extrudate in the channel by cooling to a temperature lower than the crystallization temperature of the polyglycolic acid by cooling means.
(Iii) The said manufacturing method which further includes the process 5 which heat-processes the polyglycolic acid solidification extrusion molding obtained at the said process 4 at the temperature of 150-230 degreeC for 3 to 24 hours.
(Iv) The said manufacturing method whose said resin material is a polyglycolic acid composition containing 0.001-5 mass% coloring agent on the basis of whole quantity.
(V) The above production method, wherein the resin material is a polyglycolic acid composition containing 5 to 70% by mass of a filler based on the total amount.
(Vi) The said manufacturing method which obtains the polyglycolic acid solidification extrusion molding whose tensile strength in the temperature of 150 degreeC which has a shape of a round bar, a hollow, or a flat plate is 20-200 Mpa.

  In addition, according to the present invention, the oil drilling downhole further includes the step 6 of machining the polyglycolic acid-solidified extrudate having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. produced by the above production method. A method of manufacturing a tool or member thereof is provided.

According to the present invention, polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity of 100 to 2,000 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is contained. By being a polyglycolic acid solidified extruded product formed from a resin material and having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa, a secondary molded product having a desired shape by machining such as cutting, drilling, and cutting, in particular, Decomposable resin-solidified extruded product having sufficient strength in a high-temperature environment that can be molded into a downhole tool member or the like provided in the seal plug, and a seal plug including the downhole tool member, And the effect that the core rod of a sealing plug can be provided is produced. In addition, according to the manufacturing method of the present invention, residual stress is reduced, and the hardness, strength, flexibility, etc. are excellent, and it is suitable for machining to a secondary molded product, particularly a downhole tool for oil drilling or its member. A decomposable resin-solidified extruded product having various properties and having sufficient strength in a high temperature environment can be provided.

1. Polyglycolic acid solidified extrudate The polyglycolic acid solidified extrudate of the present invention has a weight average molecular weight of 100,000 to 300,000, a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 100 to 100. It is a polyglycolic acid solidified extruded product formed from a resin material containing 2,000 Pa · s polyglycolic acid and having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa.

The polyglycolic acid used in the present invention is a polymer containing a repeating unit represented by (formula 1)-(— O—CH ₂ —CO —) —. In the polymer, the proportion of the repeating unit represented by (Formula 1) is usually 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, particularly preferably. It is 95 mass% or more, Most preferably, it is 99 mass% or more. When the ratio of the repeating unit represented by (Formula 1) is less than 50% by mass, the toughness, crystallinity, heat resistance, hardness, gas barrier properties and the like tend to decrease. In many cases, it is most preferable to use a homopolymer of polyglycolic acid in which the ratio of the repeating unit represented by (Formula 1) is 100% by mass.

  Polyglycolic acid can be produced by condensation polymerization of glycolic acid or ring-opening polymerization of glycolide. The repeating unit other than the repeating unit represented by (Formula 1) is preferably a repeating unit derived from a cyclic monomer such as ethylene oxalate, lactide, lactones, trimethylene carbonate, 1,3-dioxane, It is not limited to these.

  By introducing the repeating unit derived from the cyclic monomer at a ratio of 1% by mass or more, the melting temperature of polyglycolic acid can be lowered to lower the processing temperature, thereby reducing the thermal decomposition at the time of melt processing. be able to. Also, the extrusion rate can be improved by controlling the crystallization rate of polyglycolic acid by copolymerization. On the other hand, if too many repeating units are derived from the cyclic monomer, the crystallinity inherent to polyglycolic acid is impaired, and the toughness and heat resistance of the resulting solidified extruded product may be significantly reduced.

The polyglycolic acid used in the present invention is preferably a high molecular weight polymer. That is, the weight average molecular weight of the polyglycolic acid used in the present invention is 100,000 to 300,000, preferably 110,000 to 290,000, more preferably 120,000 to 280,000, still more preferably. 140,000 to 270,000, particularly preferably 150,000 to 260,000. Furthermore, the melt viscosity of the polyglycolic acid used in the present invention measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is 100 to 2,000 Pa · s, preferably 250 to 1,600 Pa · s, more preferably. 500 to 1,400 Pa · s, more preferably 750 to 1,300 Pa · s, particularly preferably 910 to 1,200 Pa · s.

The weight average molecular weight of polyglycolic acid is measured by the following method. That is, 10 mg of a sample is dissolved in hexafluoroisopropanol (HFIP) in which sodium trifluoroacetate is dissolved at a concentration of 5 mM to make 10 mL, and then filtered through a membrane filter to obtain a sample solution. 10 μL of this sample solution is injected into a gel permeation chromatography (GPC) apparatus, and the molecular weight is measured under the following conditions. The sample solution is injected into the GPC apparatus within 30 minutes after dissolution.
<GPC measurement conditions>
Equipment: LC-9A manufactured by Shimadzu Corporation
Column: Showa Denko HFIP-806M 2 (series connection)
Precolumn: HFIP-LG 1 column temperature: 40 ° C
Eluent: HFIP solution in which sodium trifluoroacetate is dissolved at a concentration of 5 mM Flow rate: 1 mL / min Detector: Differential refractometer Molecular weight calibration: Polymethyl methacrylate of 5 standard molecular weights with different molecular weights (manufactured by POLYMER LABORATORIES Ltd.) ) Is used for the molecular weight calibration curve data.

The melt viscosity of polyglycolic acid measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is measured by the following method. That is, an amorphous sheet of polyglycolic acid having a thickness of about 0.2 mm is crystallized by heating at about 150 ° C. for 5 minutes to obtain a sample. Using this sample, the melt viscosity of the sample is measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ using a nozzle mounted capillograph (manufactured by Toyo Seiki Co., Ltd.) with D = 0.5 mm and L = 5 mm.

  If one or both of the weight average molecular weight and the melt viscosity of polyglycolic acid are too low, melt extrusion and solidification extrusion will become difficult, and the flexibility and toughness of the resulting solidified extrusion will decrease. Cracks are likely to occur during processing. Further, if one or both of the weight average molecular weight and the melt viscosity of polyglycolic acid are too low, cracks may occur during heat treatment (annealing) of the solidified extruded product. If one or both of the weight average molecular weight and the melt viscosity of the polyglycolic acid are too high, the polyglycolic acid is likely to be thermally deteriorated because it must be heated to a high temperature during melt extrusion.

  The resin material used in the present invention is a resin composition containing polyglycolic acid as a main component. The main component means that the content of polyglycolic acid in the resin component is usually 50% by mass or more, preferably 70% by mass or more, more preferably 80% by mass or more, and further preferably 90% by mass or more. . Examples of other resin components include thermoplastic resins other than polyglycolic acid, for example, other biodegradable resins such as polylactic acid. Of course, a resin composition in which the content of polyglycolic acid in the resin component is 100% by mass may be used.

  The resin material used in the present invention may contain a colorant such as a dye or a pigment. By using a colorant, it is possible to obtain a polyglycolic acid-solidified extruded product that has a high-class feeling and is easy to perform machining such as cutting. As the colorant, a pigment is preferable in terms of excellent heat resistance. As the pigment, pigments of various colors used in the technical field of synthetic resins, such as a yellow pigment, a red pigment, a white pigment, and a black pigment, can be used. Among these pigments, carbon black is particularly preferable. Examples of carbon black include acetylene black, oil furnace black, thermal black, and channel black.

  The resin material used in the present invention is preferably a polyglycolic acid composition containing 0.001 to 5% by mass of a colorant based on the total amount. The content ratio of the colorant is preferably 0.01 to 3% by mass, more preferably 0.05 to 2% by mass. The colorant can be melt-kneaded with polyglycolic acid, but if desired, a polyglycolic acid composition (masterbatch) having a high concentration of colorant is prepared, and this masterbatch is diluted with polyglycolic acid. A resin material having a desired colorant concentration can also be prepared. From the viewpoint of uniform dispersibility of the colorant, it is preferable to prepare a resin material in which polyglycolic acid and the colorant are melt-kneaded and pelletized.

  The resin material used in the present invention can contain a filler for the purpose of improving mechanical strength and heat resistance. As the filler, a fibrous filler or a granular or powder filler can be used, but a fibrous filler is preferable.

  Examples of the fibrous filler include inorganic fibers such as glass fiber, carbon fiber, asbestos fiber, silica fiber, alumina fiber, zirconia fiber, boron nitride fiber, silicon nitride fiber, boron fiber, potassium titanate fiber; stainless steel, aluminum Metal fiber materials such as titanium, steel, and Shinshu; high melting point organic fiber materials such as aramid fiber, kenaf fiber, polyamide, fluororesin, polyester resin, and acrylic resin. As the fibrous filler, short fibers having a length of 10 mm or less, more preferably 1 to 6 mm, still more preferably 1.5 to 4 mm are preferable, inorganic fibrous materials are preferably used, and glass fibers are particularly preferable. preferable.

  Granular or powder fillers include mica, silica, talc, alumina, kaolin, calcium sulfate, calcium carbonate, titanium oxide, ferrite, clay, glass powder (such as milled glass fiber), zinc oxide, nickel carbonate, iron oxide, Quartz powder, magnesium carbonate, barium sulfate and the like can be used.

  These fillers can be used alone or in combination of two or more. The filler may be treated with a sizing agent or a surface treatment agent as necessary. Examples of the sizing agent or surface treating agent include functional compounds such as epoxy compounds, isocyanate compounds, silane compounds, and titanate compounds. These compounds may be used after being subjected to surface treatment or sizing treatment on the filler in advance, or may be added simultaneously with the preparation of the resin composition.

  When the resin material contains a filler, the content of the filler is 5 to 70% by mass, preferably 10 to 60% by mass, more preferably 15 to 50% by mass, and still more preferably 20 to 40% by mass. %. The filler can be melt-kneaded with polyglycolic acid, but if desired, a polyglycolic acid composition (masterbatch) with a high concentration of filler is prepared, and this masterbatch is diluted with polyglycolic acid. A resin material having a desired filler concentration can also be prepared. From the viewpoint of uniform dispersibility of the filler, it is preferable to prepare a resin material in which polyglycolic acid and the filler are melt-kneaded and pelletized.

  In the resin material used in the present invention, as other additives than the above, for example, impact modifiers, resin modifiers, mold corrosion inhibitors such as zinc carbonate and nickel carbonate, lubricants, thermosetting resins, oxidation Inhibitors, ultraviolet absorbers, nucleating agents such as boron nitride, flame retardants, and the like can be added as appropriate.

[Tensile strength at a temperature of 150 ° C]
The tensile strength at 150 ° C. of the polyglycolic acid-solidified extruded product of the present invention (hereinafter sometimes referred to as “150 ° C. tensile strength”) is 20 to 200 MPa. The 150 ° C. tensile strength is preferably 21 to 180 MPa, more preferably 22 to 160 MPa, still more preferably 23 to 150 MPa, and particularly preferably 24 to 140 MPa.

  The 150 ° C. tensile strength of the polyglycolic acid solidified extruded product is measured in accordance with JIS K7113. In order to set the test temperature to 150 ° C., the test piece is left in an oven for measurement ( Unit: MPa).

  Since the 150 ° C. tensile strength of the polyglycolic acid-solidified extruded product of the present invention is 20 to 200 MPa, even in a high temperature environment where the temperature exceeds 100 ° C., for example, in the ground at a depth exceeding 3,000 m underground. It is possible to provide a decomposable resin-solidified extruded product having sufficient strength.

  That is, the polyglycolic acid-solidified extruded product of the present invention forms a core plug of a plug such as a flap plug, a bridge plug, a packer, and a cement retainer, and a downhole tool member for oil drilling provided in the seal plug. Therefore, it can be preferably used. In tension and / or compression of the core rod of the sealing plug, about 2,000 to 5,000 kgf (about 19,600 to 49,000 N), in many cases about 2,500 to 4,500 kgf (about 24,500). .About.44,100N) is applied to the core rod, and in particular, the above-mentioned diameter-expanded portion (engagement portion with the jig) of the core rod has a stress concentration of 2 to 5 times. 000 to 25,000 kgf (about 39,200 to 245,000 N), in many cases about 6,000 to 20,000 kgf (about 58,800 to 196,000 N), such that the temperature exceeds 100 ° C. It must be strong enough to withstand high temperatures.

Since the core rod of the sealing plug often has a hollow shape as described above, the core rod supports the high load with the cross-sectional area of the hollow cross section. If the 150 ° C. tensile strength of the polyglycolic acid solidified extruded product of the present invention is 20 MPa or more, the cross-sectional area of the hollow cross section of the core rod of the sealing plug is about 2,450 mm ² and is about 5,000 kgf (about 49,000 N). ) In the environment of a temperature of 150 ° C. [In practice, a core rod of a sealing plug having a hollow cross-sectional area of about 2,800 mm ² at a temperature of 150 ° C. It can be said that the strength is sufficient if no fracture occurs in a tensile test in which a load of about 3,500 kgf (about 34,300 N) is applied. ]. Therefore, the polyglycolic acid-solidified extruded product having a 150 ° C. tensile strength of 20 to 200 MPa according to the present invention has a normal size (under a temperature of about 100 ° C.) at a depth exceeding 3,000 m underground (temperature about 100 ° C.). It can sufficiently withstand the stress applied to the core rod of the plug having a cross-sectional area. In many cases, it is difficult to produce or machine a polyglycolic acid-solidified extruded product having a 150 ° C. tensile strength exceeding 200 MPa.

  The shape and size of the polyglycolic acid solidified extrudate of the present invention are not particularly limited, but for example, the solidified extrudate having a thickness or diameter of 5 to 500 mm, preferably 20 to 300 mm, more preferably 30 to 200 mm. Can be obtained. In addition, solid extruded products with various shapes such as round bars, flat plates, hollow products such as pipes, and irregular shaped products can be obtained, but solidified extrusion and subsequent densification treatment are easy and machine processing is also possible. It is preferably in the shape of a round bar, hollow, or flat plate because it is often suitable for a solidified extruded product, and is a downhole tool for oil drilling or a downhole tool member for oil drilling, which will be described later, particularly a sealing plug. For forming the core rod, a round bar shape is more preferable.

The density of the polyglycolic acid-solidified extrudate of the present invention is a polyglycolic acid-solidified extrudate formed from a resin material containing the polyglycolic acid and having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa. (The density of the resin part other than the filler part) is not particularly limited, but is preferably 1,570 to 1,610 kg / m ³ , more preferably 1,575 to 1,605 kg / m ³ , and still more preferably. It is 1,577 to 1,603 kg / m ³ , particularly preferably 1,580 to 1,600 kg / m ³ . If the density of the polyglycolic acid solidified extruded product is too low, the strength, hardness, toughness, flexibility and the like are lowered, and cracks are likely to occur during machining such as cutting, drilling and cutting. If the density of the polyglycolic acid-solidified extruded product is too high, it is difficult to produce.

The polyglycolic acid-solidified extruded product of the present invention may have different densities in the surface portion and the central portion (in the case of a hollow shape, the inner peripheral portion). The density difference between the surface portion and the central portion is preferably 0.5 to 50 kg / m ³ , more preferably 1.5 to 20 kg / m ³ , still more preferably 2.0 to 10 kg / m ³ , particularly preferably. The range is 2.5 to 5 kg / m ³ . If the difference in density between the surface part and the center part of the polyglycolic acid-solidified extruded product is within the above range, a machining material with excellent machinability can be obtained and formed by machining such as cutting. It is preferable because the shape of the formed secondary product can be precisely controlled.

2. Production method of polyglycolic acid-solidified extruded product The polyglycolic acid-solidified extruded product of the present invention can be produced by a production method including steps 1 to 4 shown in the following a) to d).

a) A resin material containing polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 100 to 2,000 Pa · s, Step 1 of supplying to an extruder and melt-kneading at a cylinder temperature of 220 to 285 ° C. of the extruder;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the forming die direction, and at this time, expansion in the thickness direction or diameter direction of the solidified extrudate is suppressed by pressurization to obtain a polyglycolic acid solidified extrudate. Step 4;
The manufacturing method of the polyglycolic acid solidification extrusion molding whose tensile strength in the temperature of 150 degreeC containing 20-200 Mpa is included.

  According to the present invention, the weight average molecular weight and melt viscosity of polyglycolic acid, the method of supplying the material to the extruder, the melt kneading conditions, the extrusion conditions and cooling conditions, the back pressure conditions and the pressurizing conditions loaded on the solidified extrudate, Furthermore, a polyglycolic acid solidified extruded product having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa can be obtained by adjusting the heat treatment conditions described later in combination. Below, the manufacturing process in case the polyglycolic acid solidification extrusion molding of this invention is a round bar or the shape of a flat plate is demonstrated. Other shapes of polyglycolic acid-solidified extruded products can be produced in the same manner.

  First, in step 1, the resin material containing polyglycolic acid may be supplied to a hopper attached to the supply unit of the extruder, but preferably the resin material containing polyglycolic acid is used with a quantitative feeder. To supply to the extruder. That is, a fixed amount feeder is installed, a resin material is charged into the hopper, and the resin material is supplied from the fixed amount feeder to the supply unit (hopper) of the extruder at a constant speed. Pellets are preferably used as the resin material. It is preferable that the resin material is sufficiently dried and dehumidified before molding. The dehumidifying and drying conditions are not particularly limited. For example, it is preferable to employ a method of holding the pellets at 100 to 160 ° C. for about 1 to 24 hours in a dry heat atmosphere.

  Subsequently, in step 1, the resin material is melt-kneaded in the cylinder of the extruder. The cylinder temperature is adjusted to 220 to 285 ° C, preferably 225 to 275 ° C, more preferably 227 to 273 ° C. When a plurality of heating means are arranged in the extruder cylinder corresponding to the solid phase resin transport section, the melting section, the liquid phase resin transport section, etc., the temperature of each heating means is made different from each other within the above range. Alternatively, the temperature of each heating means may be controlled to the same temperature.

  In the step 2, the resin material melted by melt kneading is melt-extruded from the extrusion die at the tip of the extruder. The molten resin material from the extrusion die is extruded into the flow path of the forming die provided with a flow path communicating with the molten resin passage of the extrusion die and having a cross-sectional shape of the extruded product, and cooling means. The cross-sectional shape of the extrudate is a rectangle when the extrudate is a flat plate, and a circle when it is a round bar.

  In the step 3, the molten extrudate made of the resin material is cooled and solidified in the flow path of the forming die, and then the solidified extrudate is extruded from the tip of the forming die to the outside. The extrusion speed is usually 5 to 50 mm / 10 minutes, preferably 10 to 40 mm / 10 minutes.

  In the step 3, a forming die having heating means in addition to cooling means is used. First, the molten extrudate in the flow path near the exit of the extrusion die is heated at 230 to 290 ° C., preferably 240 to 240 ° C. It is possible to employ a method of heating to a temperature of 285 ° C. and then cooling and solidifying the molten extrudate in the flow path, particularly its surface portion, to a temperature lower than the crystallization temperature of the polyglycolic acid by a cooling means. preferable. When the temperature near the exit of the extrusion die is rapidly cooled, the progress of crystallization of polyglycolic acid may be slow. By heating the temperature in the vicinity of the extrusion die to the above range and then cooling, the crystallization of the molten extrudate, particularly its surface portion, can be promoted. Even when the outlet temperature of the extrusion die is within the above range, the temperature of the melted extrudate, particularly the surface portion thereof, in the flow path near the extrusion die outlet can be within the above range.

  By the cooling means, the temperature of the extrudate, particularly the surface portion thereof is cooled to a temperature lower than the crystallization temperature of polyglycolic acid and solidified. The crystallization temperature of polyglycolic acid (the crystallization temperature detected when the temperature is lowered from the molten state) is usually about 130 to 140 ° C. The cooling temperature of the cooling means is preferably 100 ° C. or lower, more preferably 95 ° C. or lower. The lower limit of the cooling temperature is preferably 40 ° C, more preferably 50 ° C. When the resin material used in step 1 contains a filler such as glass fiber, the crystallization temperature of polyglycolic acid may increase due to melt-kneading in the cylinder of the extruder. The temperature is preferably within the above range.

  The heating means includes, for example, a heater as a heating source. The cooling means includes, for example, a water cooling pipe that can circulate cooling water as a refrigerant.

  In step 4, the solidified extrudate is pressurized and taken out while applying a back pressure in the forming die direction. At this time, the solidified extrudate is suppressed from expanding in the thickness direction or the diameter direction by pressurization. A glycolic acid solidified extrudate is obtained. Examples of the pressing means include a combination of an upper roll group and a lower roll group. The solidified extrudate can be pressurized by a method in which a lower roll group is placed on a table and a load is applied to the upper roll group. The solidified extrudate may be pressurized by applying a load in the upper direction to the lower roll group and applying a load in the lower direction to the upper roll group.

  By applying pressure to the solidified extrudate extruded from the forming die by a roll group in which a plurality of rolls are combined from the discharge port of the forming die, the expansion of the solidified extrudate in the thickness direction or the diameter direction is suppressed. At the same time, back pressure in the forming die direction can be applied. A back pressure in the direction of the forming die may be applied to the solidified extruded product in combination with an appropriate loading means. The magnitude of the back pressure is usually in the range of 1,500 to 8,500 kg, preferably 1,600 to 8,000 kg, more preferably 1,800 to 7,000 kg, still more preferably 2,000 to 6,000 kg. When the diameter or thickness of the solidified extruded product is large, it is preferable to increase the applied back pressure. This back pressure can be measured as the die external pressure (pressure applied to the flow path).

  By suppressing the expansion in the thickness direction or the diameter direction of the solidified extrudate by this pressurization, as a solidified extrudate finally obtained, a polyglycolic acid solidified having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa. Extrudates can be produced. After pressing, the solidified extrusion is taken up.

  When the solidified extruded product is a round bar, in addition to the method of applying pressure by combining the upper roll group and the lower roll group described above, a roll group surrounding the round bar-shaped solidified extruded product is arranged. There is also a method of applying pressure in the center direction to the roll group. The method of pressurizing the solidified extrudate discharged from the forming die can apply a back pressure in the direction of the forming die, and suppresses expansion in the thickness direction or the diameter direction of the solidified extrudate by pressurization, for example, As long as the thickness or diameter of the finally obtained solidified extruded product is 5 to 500 mm, preferably 20 to 300 mm, more preferably 30 to 200 mm, any method can be used. The method can be adopted.

  It is preferable that the polyglycolic acid extruded product obtained in the step 4 is annealed by arranging a step 5 of heat treatment at a temperature of 150 to 230 ° C. for 3 to 24 hours. By this annealing treatment, it is possible to remove the residual stress of the solidified extruded product, and to prevent inconvenience such as deformation in the solidified extruded product itself and the secondary molded product after machining. The heat treatment temperature is preferably 175 to 225 ° C, more preferably 185 to 220 ° C. The heat treatment time is preferably 4 to 20 hours, more preferably 5 to 15 hours.

  The polyglycolic acid solidified extrudate produced by the production method of the present invention can have various shapes such as hollow rods, pipes, etc., flat plates, irregular shapes, etc., but solidified extrusion and subsequent densification treatment. In view of ease of processing, it is often suitable as a material for machining, and is easy to process the core member of the sealing member, which is a preferred application, and has a round bar, hollow or flat plate shape. It is preferably a round bar or a hollow shape.

  Typical machining that can be performed on the polyglycolic acid-solidified extrusion is cutting, drilling, cutting, and combinations thereof. A broad-cutting method may include drilling as well as cutting. Cutting methods include turning using a single-edged tool, grinding, planing, and boring. Cutting methods using multiple blades include milling, drilling, threading, gear cutting, mold carving, and file processing. In the present invention, drilling using a drill or the like may be distinguished from cutting. Cutting methods include cutting with a blade (saw), cutting with abrasive grains, and cutting by heating and melting. In addition, a grinding finishing method, a plastic working method such as punching using a knife-like tool or scribing, and a special processing method such as laser processing can also be applied.

  If the polyglycolic acid solidified extruded product, which is a material for machining, is a flat plate, round bar or hollow shape having a large wall thickness, generally the solidified extruded product is made into an appropriate size or thickness for machining. The cut and solidified extruded product is ground and trimmed to a desired shape, and further, drilling is performed at a necessary portion. Finally, finish processing is performed if necessary. However, the order of machining is not limited to this. When the solidified extruded product is melted by frictional heat during machining and it is difficult to produce a smooth surface, it is desirable to perform machining while cooling the cutting surface. If the solidified extruded product excessively generates heat due to frictional heat, it causes deformation and coloring. Therefore, the solidified extruded product or the processed surface is preferably controlled to a temperature of 200 ° C. or lower, more preferably 150 ° C. or lower. .

3. Material for machining The polyglycolic acid solidified extruded product having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. according to the present invention is used for secondary processing of various resin parts by performing machining such as cutting, drilling and cutting. It can be set as the raw material for machining for shape | molding in a molded object. Examples of the secondary molded product include various members (downhole tool or its members) used for downholes used for excavation of hydrocarbon resources such as oil and gas. That is, examples of the secondary molded product include a downhole tool for oil drilling formed from a degradable material or a downhole tool member for oil drilling provided in the downhole tool. For example, it is a downhole tool for oil drilling or a member thereof formed by machining a polyglycolic acid solidified extruded product having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. of the present invention, such as cutting. Particularly preferred is a sealing plug comprising a downhole tool member for oil drilling formed by machining a polyglycolic acid solidified extruded product having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. of the present invention. . Another particularly preferred example is a core rod of a sealing plug formed from a polyglycolic acid solidified extruded product having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. of the present invention. By further including the step 6 of machining the polyglycolic acid solidified extruded product having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. of the present invention, a downhole tool for oil drilling or a member thereof can be produced, Specifically, for example, a round bar having a diameter of 20 to 200 mm for forming a downhole tool for oil drilling or a member thereof, a hollow tube having an outer diameter of 50 to 200 mm and an inner diameter of 5 to 100 mm can be obtained. . Further, a hollow tube having a uniform inner diameter as a hollow tube and a shape in which the outer diameter of a part, for example, an end portion is expanded can be obtained.

  The polyglycolic acid-solidified extruded product of the present invention can be formed into other secondary molded products by machining. For example, in the electric and electronic field, wafer carrier, wafer cassette, spin chuck, tote bin, wafer boat, IC chip tray, IC chip carrier, IC transfer tube, IC test socket, burn-in socket, pin grid array socket, quad flat package, lead Examples include less chips carriers, dual in-line packages, small outline packages, reel packing, various cases, storage trays, transport device parts, and magnetic card readers.

  In the field of OA equipment, various roll members in image forming apparatuses such as electrophotographic copying machines and electrostatic recording apparatuses, transfer drums for recording apparatuses, printed circuit board cassettes, bushes, paper and bill transport parts, paper feed rails, font cartridges, Ink ribbon canisters, guide pins, trays, rollers, gears, sprockets, computer housings, modem housings, monitor housings, CD-ROM housings, printer housings, connectors, computer slots, and the like.

  In the field of communication equipment, mobile phone parts, pagers, various sliding materials and the like can be mentioned. In the automotive field, interior materials, under hoods, electronic / electric equipment housings, gas tank caps, fuel filters, fuel line connectors, fuel line clips, fuel tanks, equipment beads, door handles, various parts and the like can be mentioned. In other fields, electric wire supports, radio wave absorbers, flooring materials, pallets, shoe soles, brushes, blower fans, planar heating elements, polyswitches, and the like can be given.

  Hereinafter, the present invention will be described more specifically with reference to Examples, Comparative Examples, and Reference Examples. The present invention is not limited to the examples. The measurement methods of physical properties and characteristics are as follows.

(1) Weight average molecular weight of polyglycolic acid The weight average molecular weight of polyglycolic acid was measured by the following method. That is, 10 mg of a sample was dissolved in hexafluoroisopropanol (HFIP) in which sodium trifluoroacetate was dissolved at a concentration of 5 mM to make 10 mL, and then filtered through a membrane filter to obtain a sample solution. 10 μL of this sample solution was injected into a gel permeation chromatography (GPC) apparatus, and the molecular weight was measured under the following conditions. The sample solution was injected into the GPC apparatus within 30 minutes after dissolution.
<GPC measurement conditions>
Equipment: LC-9A manufactured by Shimadzu Corporation
Column: Showa Denko HFIP-806M 2 (series connection)
Precolumn: HFIP-LG 1 column temperature: 40 ° C
Eluent: HFIP solution in which sodium trifluoroacetate is dissolved at a concentration of 5 mM Flow rate: 1 mL / min Detector: Differential refractometer Molecular weight calibration: Polymethyl methacrylate of 5 standard molecular weights with different molecular weights (manufactured by POLYMER LABORATORIES Ltd.) ) Is used for the molecular weight calibration curve data.

(2) Melt viscosity of polyglycolic acid Using a sample obtained by crystallizing an amorphous sheet of polyglycolic acid having a thickness of about 0.2 mm at about 150 ° C. for 5 minutes, D = 0.5 mm, L = 5 mm The melt viscosity of the sample was measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ using a nozzle-equipped capillograph [Capiro 1A manufactured by Toyo Seiki Seisakusho Co., Ltd.].

(3) Density A sample cut out from the polyglycolic acid solidified extruded product was measured according to JIS R 7222 (pycnometer method using n-butanol) (average value of three samples).

(4) Tensile strength at a temperature of 150 ° C. The measurement of the 150 ° C. tensile strength of the polyglycolic acid-solidified extruded product is based on JIS K7113, using a 2t autograph AG-2000E manufactured by Shimadzu Corporation as a test piece. Was performed in an oven at a temperature of 150 ° C. (unit: MPa).

(5) Practical confirmation test A hollow body produced by machining (cutting) a polyglycolic acid-solidified extruded product is incorporated in a sealing plug as a core plug of a sealing plug, and is heated in a heating oven at a temperature of 150 ° C. A tensile test was conducted at 3,500 kgf (34,300 N) to confirm whether the core rod was broken or not.

[Example 1]
A pellet of polyglycolic acid having a weight average molecular weight of 230,000, a temperature of 270 ° C. and a shear viscosity of 920 Pa · s measured at a shear rate of 120 sec ⁻¹ was held at a temperature of 140 ° C. for 6 hours and dehumidified and dried. The dehumidified and dried pellets are supplied to the hopper with a fixed feeder, supplied at a constant speed to the supply part of a 30 mmφ single-screw extruder with L / D = 20, melt-kneaded at a cylinder temperature of 251 ° C., and extrusion die At an outlet temperature of 276 ° C., it was melt extruded into the forming die flow path, and cooled at a cooling temperature of 90 ° C. to be solidified. The extrusion speed was about 19 mm / 10 minutes.

  By pressing the solidified extruded product solidified in the flow path of the forming die between the upper roll group and the lower roll group and adjusting the pressure to the forming die external pressure (back pressure) of 3,100 kg, polyglycol Swelling of the acid-solidified extrusion was suppressed. Next, the solidified extrusion was heat treated at a temperature of 215 ° C. for 6 hours to remove residual stress. The heat treatment did not cause cracking or deformation in the solidified extruded product.

By this method, a round bar-shaped polyglycolic acid solidified extruded product having a diameter of 90 mm and a length of 1,000 mm was obtained. When a test piece was cut out from the obtained round bar and the tensile strength at 150 ° C. was measured, it was 38 MPa. Moreover, about the sample (three pieces) cut out radially in the position of 5 mm from the both ends of a length direction, and the position of a center part about the obtained round bar, the outer surface part and center part (radius of 10 mm of a radial direction) The density of the outer surface portion was 1,581.1 kg / m ³ , and the density of the central portion was 1,584.2 kg / m ³ .

  From the round bar, the outer diameter is machined (cutting) using a punching process and a high-speed tool, and the range of 200 mm from both ends is an outer diameter of 90 mm and an inner diameter of 20 mm, and the remaining 600 mm is an outer diameter of 80 mm and an inner diameter of 20 mm. A hollow body was produced. There was no streak-like flow pattern due to insufficient kneading in the cut cross section without inducing cracks during processing, and it was uniform and beautiful.

  The produced hollow body was assembled into a sealing plug as a core rod of a sealing plug, and a tensile test was conducted at 3,500 kgf (34,300 N) in a heating oven at a temperature of 150 ° C. Did not occur. Moreover, there was no problem in the closing operation.

[Example 2]
A mass ratio of polyglycolic acid having a weight average molecular weight of 230,000, a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ and having a melt viscosity of 920 Pa · s and glass fiber (Owens Corning, 03JAFT592S, length 3 mm) is 70 : A resin material pellet prepared by melting and kneading at 30 was used in the same manner as in Example 1 except that the material was dehumidified and dried at a temperature of 120 ° C. for 6 hours. A round bar-shaped polyglycolic acid solidified extruded product having a length of 1,000 mm was obtained. When a test piece was cut out from the obtained round bar and the tensile strength at 150 ° C. was measured, it was 45 MPa.

  From the obtained round bar, a hollow body having the same shape as that of Example 1 was manufactured by performing the same punching process as in Example 1 and cutting of an outer diameter using a high speed bite. There was no streak-like flow pattern due to insufficient kneading in the cut cross section without inducing cracks during processing, and it was uniform and beautiful. The produced hollow body was assembled into a sealing plug as a core rod of a sealing plug, and a tensile test was conducted at 3,500 kgf (34,300 N) in a heating oven at a temperature of 150 ° C. Did not occur. Moreover, there was no problem in the closing operation.

[Comparative Example 1]
In the same manner as in Example 1, except that polyglycolic acid pellets having a melt viscosity of 95 Pa · s measured at a weight average molecular weight of 70,000, a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ were used as raw materials. Obtained a round bar-shaped polyglycolic acid solidified extruded product having a length of 90 mm and a length of 1,000 mm. In the process of heat treatment at a temperature of 215 ° C. for 6 hours, some deformation such as constriction was observed. When a test piece was cut out from the obtained round bar and the 150 ° C. tensile strength was measured, it was 10 MPa.

  From the obtained round bar, a hollow body having the same shape as that of Example 1 was manufactured by performing the same punching process as in Example 1 and cutting of an outer diameter using a high speed bite. Although no cracking was induced during processing, a streak-like flow pattern due to insufficient kneading was observed on the cut section. The produced hollow body was assembled into a sealing plug as a core rod of a sealing plug, and when a tensile test was conducted at 3,500 kgf (34,300 N) in a heating oven at a temperature of 150 ° C., the core rod was broken. However, the sealing mechanism was not expressed.

From Example 1 and Example 2, a polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity of 100 to 2,000 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ is obtained. The polyglycolic acid solidified extruded product formed from the resin material it contains and has a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa has excellent machinability and is secondary by machining such as cutting, drilling, and cutting. It has been found that it is possible to mold a molded article, especially a downhole tool member for oil drilling. On the other hand, it was formed from a resin material containing polyglycolic acid having a weight average molecular weight of 70,000, a melt viscosity of 95 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ , and a tensile strength at a temperature of 150 ° C. The polyglycolic acid solidified extruded product of Comparative Example 1 having a strength of 10 MPa is deformed by heat treatment performed for stress relaxation, and a beautiful processed surface cannot be obtained by cutting or cutting mechanical processing. In particular, it has been found that the strength in a high temperature environment required for the use of an oil drilling downhole tool or its member is insufficient.

The polyglycolic acid solidified extruded product of the present invention has a weight average molecular weight of 100,000 to 300,000, and a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 100 to 2,000 Pa · s. A polyglycolic acid-solidified extruded product formed from a resin material containing polyglycolic acid and having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C. allows the desired shape to be obtained by machining such as cutting, drilling, and cutting. Decomposable resin-solidified extruded product having sufficient strength in a high temperature environment that can be molded into a next molded product, particularly a downhole tool member provided in a sealing plug, and the downhole tool member Can be provided, and the core rod of the plug can be provided, so that the industrial applicability is high. . In addition, according to the manufacturing method of the present invention, residual stress is reduced, and the hardness, strength, flexibility, etc. are excellent, and it is suitable for machining to a secondary molded product, particularly a downhole tool for oil drilling or its member. Since a decomposable resin-solidified extruded product having various properties and sufficient strength in a high temperature environment can be provided, the industrial applicability is high.

Claims (16)

Formed from a resin material containing polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity of 100 to 2,000 Pa · s measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ , A polyglycolic acid solidified extruded product having a tensile strength at a temperature of 150 ° C. of 20 to 200 MPa.   The polyglycolic acid solidified extruded product according to claim 1, which has a round bar, hollow or flat plate shape.   The polyglycolic acid-solidified extruded product according to claim 1 or 2, wherein the resin material is a polyglycolic acid composition containing 0.001 to 5% by mass of a colorant based on the total amount.   The polyglycolic acid-solidified extruded product according to any one of claims 1 to 3, wherein the resin material is a polyglycolic acid composition containing 5 to 70% by mass of a filler based on the total amount.   The polyglycolic acid solidified extruded product according to any one of claims 1 to 4, which is a material for machining.   A downhole tool for oil drilling or a member thereof formed by machining the polyglycolic acid-solidified extruded product according to claim 5.   A sealing plug comprising a downhole tool member for oil drilling formed from the polyglycolic acid solidified extruded product according to claim 6.   The downhole tool member for oil drilling according to claim 6, wherein the downhole tool member is a core rod of a sealing plug. The following steps 1 to 4;
a) A resin material containing polyglycolic acid having a weight average molecular weight of 100,000 to 300,000, a melt viscosity measured at a temperature of 270 ° C. and a shear rate of 120 sec ⁻¹ of 100 to 2,000 Pa · s, Step 1 of supplying to an extruder and melt-kneading at a cylinder temperature of 220 to 285 ° C. of the extruder;
b) Forming provided with a cooling means and a flow path in which the resin material melted by melt kneading from the extrusion die at the tip of the extruder communicates with the molten resin passage of the extrusion die and has a cross-sectional shape of the extruded product Extruding into the flow path of the die 2;
c) Step 3 of cooling and solidifying the molten extrudate made of a resin material in the flow path of the forming die and then extruding the solidified extrudate from the tip of the forming die; and d) the solidified extrudate. Is taken up while applying back pressure in the forming die direction, and at this time, expansion in the thickness direction or diameter direction of the solidified extrudate is suppressed by pressurization to obtain a polyglycolic acid solidified extrudate. Step 4;
The manufacturing method of the polyglycolic acid solidification extrusion molding whose tensile strength in the temperature of 150 degreeC containing 20-200 Mpa is included.   The manufacturing method of Claim 9 which supplies the resin material containing the said polyglycolic acid in the said process 1 to an extruder using a fixed quantity feeder.   In step 3, a forming die having heating means in addition to cooling means is used. First, the molten extrudate in the flow path near the extrusion die outlet is heated to a temperature of 230 to 290 ° C. by the heating means. The method according to claim 9 or 10, wherein the molten extrudate in the flow path is then cooled to a temperature lower than the crystallization temperature of the polyglycolic acid and solidified by cooling means.   The manufacturing method of any one of Claims 9 thru | or 11 which further includes the process 5 which heat-processes the polyglycolic acid solidification extrusion molding obtained by the said process 4 at the temperature of 150-230 degreeC for 3 to 24 hours.   The manufacturing method according to any one of claims 9 to 12, wherein the resin material is a polyglycolic acid composition containing 0.001 to 5% by mass of a colorant based on the total amount.   The production method according to any one of claims 9 to 13, wherein the resin material is a polyglycolic acid composition containing 5 to 70% by mass of a filler based on the total amount.   The production method according to any one of claims 9 to 14, wherein a polyglycolic acid-solidified extruded product having a round bar, hollow or flat plate shape and a tensile strength at a temperature of 150 ° C of 20 to 200 MPa is obtained.   Oil drilling further comprising step 6 of machining a polyglycolic acid solidified extrudate having a tensile strength of 20 to 200 MPa at a temperature of 150 ° C produced by the production method according to any one of claims 9 to 15. A method for manufacturing a downhole tool or a member thereof.